Any refinery process water, petroleum chemical waste water, ballast waste water, river water, underground feed water, ethylene quench waste water, oil-in-water waste emulsions from oil recovery fields, and the like are contaminated waters requiring difficult chemical treatment and clarification. These aqueous systems are also found in steam cylinder dispersions in which small amounts of oils which are used for lubrication may be found in the steam of engines and pumps; emulsions and other dispersions containing polystyrene and styrenes-in-water frequently found in synthetic rubber manufacturing facilities; emulsions and other dispersions obtained during clay pipe manufacture using steam initiated processes; oil-in-water emulsions or dispersions which are found in coolant water devices and in gasoline absorption facilities; emulsions and dispersions containing wax-type products which are encountered in oil refinery dewaxing procedures; "fluxoil" emulsions and dispersions occurring in condensate steam resulting in dehydrogenation of butylene during catalytic procedures to produce butadiene; emulsions and dispersions obtained during procedures for making butadiene from naphtha by means of standard "cracking" procedures in gas generators; emulsions and dispersions in latex-in-water formed in copolymerization procedures for butadiene and styrene derivatives.
Such dispersions and emulsions are also problems in synthetic resin paint and pigment manufacturing processes, as well as in food processing of derivatives of pasteurized additives. In each of these processes, as well as in the equipment which is used during steps in the various procedures, oil-in-water emulsions or dispersions of a nonaqueous phase are inherently formed as a by-product of the particular given operation. The disposal of the produced waste water becomes a problem which is compounded by the presence of the oil-in-water emulsions, or dispersions containing a non-aqueous discontinuous phase. Often, extreme difficulties are presented in the treatment and clarification processes employed. If one were to successfully treat these kinds of waste waters which contain oily waste matter as well as dispersed solid matter of an organic or inorganic nature, one could advance the art of treating and clarifying contaminated waters of this type.
The present invention is directed to the clarification of such aqueous systems, so that the resultant stream of the aqueous system contains essentially two separate phases: an oil- or hydrocarbon-based phase, or non-aqueous phase, and an essentially aqueous phase, with the resultant aqueous phase being clarified without the production of a problematic floc. Clarification is accomplished with water clarifiers which are compounds which, when added to produced water containing oil, form "flocs." The dispersed oil and solid particulates adsorb on the floc and thereby are removed from the water when the floc is skimmed off the surface of the treated water. The treated aqueous system can then pass certain industrial and/or governmental water clarity tests or specifications and be discharged.
The aqueous systems contemplated in this invention will contain water in various forms, such as tap water, brines or seawater (in the case of aqueous systems involved in the drilling, completion, workover or production of subterranean oil or gas wells), and the like.
In any oil-in-water emulsion, the amount of oil in the water or aqueous phase, or in the case of a dispersion of non-aqueous phase, the amount of such non-dispersed phase will vary considerably depending on the industrial application. In the case of emulsions which are frequently found in the oil field and in applications of well completion operations, the oil-in-water emulsion will contain a crude oil content varying from a few parts per million to about 20%, by volume, or even higher.
In treating such emulsified or dispersed aqueous systems for disposal or other uses or recycling, it is necessary to break the emulsified oil-in-water or resolve the dispersion such that the oil phase, or the non-aqueous dispersed phase and the water phase may be separated. The water should be clarified by the demulsification treatment without production of a problematic "floc."
"Floc" is considered to be a by-product of water clarification which may vary in characteristics depending on the composition of the clarifier used to clarify the water. While "floc" may always be expected to be produced as a result of a water clarification treatment procedure, such "floc" should be made to be controllable. A problematic floc may adversely affect operations or clarification systems by means of adherence, plugging and interface problems with manufacturing equipment or production equipment. Floc characteristics can be visually judged by observing a sample of the treated aqueous system. The present invention contemplates water clarification such that the floc which is formed does not cause operational problems in the treatment system by means of adherence, plugging, or interface buildup with equipment being exposed to the aqueous system. An improved floc is one that is easily skimmed and does not build up in the system--essentially, a floc which is easier to handle.
In the past, those skilled in the art have recognized the use of derivatives of certain amines as demulsifiers in water clarification procedures. Typical of such prior art is U.S. Pat. No. 4,689,177, which teaches the use of nitrogen-containing dithiocarbamic acid compositions formed by the reaction of alkoxylated triamines with CS.sub.2 as "reverse" demulsifiers. While certain of the materials disclosed in the '177 patent may or may not be used satisfactorily to demulsify particular aqueous systems, it has been found that not all such materials are satisfactory to clarify water without the production of a resultant problematic floc.
U.S. Pat. No. 4,855,060 notes that if bis(hexamethylene)triamine (BHMT) is reacted in an approximate stoichiometric ratio of primary amine with carbon disulfide, that the resultant product can be used to successfully break the emulsion and clarify the water, without the production of a problematic floc. In U.S. Pat. No. 4,855,060, these problematic flocs were termed "uncontrollable" and it will be understood that these terms refer to the same kinds of undesirable flocs. The commercial product related to the material of this patent is marketed by Baker Performance Chemicals, Inc. as MAGNACLEAR.RTM. W213 water clarifier, referred to herein as W213. MAGNACLEAR.RTM. W213 is a trademark for water clarifier products made by Baker Performance Chemicals, Inc.
On an oil and gas production site, dithiocarbamate water clarifiers work in conjunction with gravity settling equipment, flotation devices, filtration equipment and the like by creating a floc with metal ions in the brine. After the oil and grease have absorbed onto the surface of the floc, the floc is separated and returned to crude production. Most prior flocs are "sticky" and adhere to surfaces inside the equipment. After a relatively short period of time, the build-up of floc on the skimmer, walls and in the trough causes the unit to need to be shut down and cleaned. Preferably, the water clarifier provides an "acceptable" floc which does not cause operational problems in the system via adherence, plugging and interface build-up.